VSock support or examples of custom channels

### Is your feature request related to a problem? Please describe.
I am interested in using `@grpc/grpc-js` for communication between an AWS Nitro Enclave and its host. There is a lightweight package for interfacing with VSock from node called https://github.com/wei-rong-1/node-vsock

### Describe the solution you'd like
I would either like `vsock` support or an example of creating a custom Channel that could wrap the above referenced library.

### Describe alternatives you've considered
The alternative to native support is creating a custom Channel that wrapps the `node-vsock` library.